The current total market value for silver inks is estimated to be approximately $8 billion annually. A current main use for silver inks is for printing conductive lines and interconnects between electric parts in devices. Devices utilizing silver inks include, for example, home appliances, such as in control panels of the home appliances, for example for flat membrane sensors and switches, consumer electronics, computers, cell phones and solar panels.
Fabrication of electronic elements using liquid deposition techniques is of profound interest as such techniques provide potentially low-cost alternatives in applications such as thin film transistors (TFTs), light-emitting diodes (LEDs), RFID tags, photovoltaics, and the like. However the deposition and/or patterning of functional electrodes, pixel pads, and conductive traces, lines and tracks which meet the conductivity, processing, and cost requirements for practical applications have been a great challenge.
While the market for silver paste is well established in the above-mentioned applications, there are great opportunities if problems with silver ink were solved, such as low conductivity or high sheet resistance when compared with pure metals, and cost, in view of the rising cost of silver.
Thus, a performance concern with most commercially available conductive inks, for example conductive inks comprised of a conductive flake such as silver, binder and solvent, is that the conductivity is too low when compared with pure metal. For commercial silver ink pastes from suppliers such as DuPont or Henkel, a sheet resistivity of the inks ranges from 12 to 25 mΩ/sq./mil.
Conductive inks with a reduced sheet resistance would be a great enabler for the use of the inks in a wide range of products requiring exceptional conductive interconnections between electronic components, such as sensors, photovoltaic panels, flat OLED lighting and so on. Furthermore, conductive inks with increased conductivity may allow for the printing of thinner lines, therefore reducing materials costs.
There thus remains a need for conductive inks exhibiting improved sheet resistivity and conductivity.